The invention relates to a spring structure for a drum pedal.
A bass drum of prior art design is shown in FIGS. 9-13. It includes supports 92 which extend up from both lateral sides of a base 91 of a drum pedal 90. A beater rotary shaft 94 is held freely rotatably in bearings 93 at the top ends of the supports 92. At the approximate center of the beater rotary shaft 94, there is a beater member 110 on the shaft and a wheel shaped operating member 120 that rotates integrally with the beater member 110. A beater 115 is fixed on the beater member 110 by the screws 116.
The operating member 120 comprises a sprocket or a partial sprocket, having a toothed periphery on which a chain 121 is wound. One end of the chain is fixed to the operating member 120. The other end of the chain 121 is linked to the tip of a swingable foot pedal 95, which has a rear end that is pivoted to a platform or pedal base. The chain 121 is pulled down as the foot pedal 95 is stepped on, as shown by arrow A in FIG. 9. This rotates the operating member 120, which rotates the beater member 110 so that the beater 115 beats the drum surface D.
FIG. 11 shows a cam 100 which is fixed by a screw 101 at the edge of the beater rotary shaft 94. There is a shaft receiving hole 102 approximately at the center of cam 100, through which the rotary shaft 94 is inserted. A plurality of roller holes 103 are formed at circumferentially closely spaced intervals in the cam 100.
A roller installation bolt 104 is screwed into a selected one of the roller installation holes 103. A generally ring shaped spring 106 extends around a roller 105 that is installed in the roller installation bolt 104. The top end of a coil spring 107 is attached at the bottom tip of the spring 106. The lower end of the spring 107 is attached on the lower bracket 109 outside the support 92.
The spring 107 automatically restores the beater rotary shaft 94, returning the beater 115 automatically to its original position off the drum surface after it beats the drum surface D. A bearing holder 93a holds the bearing 93 on the shaft 94. An adjusting bolt at the bottom of the spring 107 adjusts the tension of the spring 107. There is a clamp 130 for holding the drum hoop.
In the spring structure, the roller 105 rotates with respect to the roller installation bolt 104 when the cam 100 rotates during beating of the drum surface D. At this juncture, the downward pull of the tension spring 107 pulls the roller 105 downward producing friction between the inner surface of the roller 105 and the outer surface of the roller installation bolt 104. This friction prevents rotation of the roller 105 so that the smooth swinging of the beater 115 becomes difficult.
Moreover, the spring 106 can be detached from the roller 105 by hand for convenience at the time of transportation, etc. As the top of the spring 107 goes through the gap G in the spring 106, however, the spring 106 may separate from the spring 107.
If the gap G of the spring 106 is made smaller to prevent the possible loss of the spring 106 through falling out, then production and assembly become more difficult.
Those members in FIG. 12 which are the same as in FIGS. 9 through 11 have the same reference numbers. To avoid the above described situation, FIG. 12 shows a design with a hole 141 at the lower part of the cam 140, with a bearing 145 arranged in the hole 141. The installation part of the spring member 150 has a groove 151 that receives a narrowed lower part of the cam 140 so that they are freely rotatably held together. The top of the spring 153 can be hooked at the opening 152 in the lower part of the spring member 150.
A spring member 150 is installed on the cam 140 through a bearing 145. Therefore, the friction experienced during rotation of the spring member 150 with respect to the cam 140 is reduced, thereby enabling the beater rotary shaft 94 to be smoothly rotated. Also, the spring 153 cannot disengage from the spring member 150.
The spring member 150 is installed on the bearing 145 of the cam member 140 through tightening of the installation bolt 155. This makes it difficult to easily remove the spring member 150 from the cam 140. As a consequence, when the beater is transported, it may be transported either as it is or in the state where the beater 115 is situated above the support 92 or the operating member 120 or when the beater 115 has been removed from the beater member 110.
If the drum pedal is to be carried as it is, the drum pedal cannot be carried in a case but has to be carried without packaging. This requires special care to avoid damaging the drum pedal when it is transported.
When the drum pedal is to be transported by removing the beater 115 from the beater member 110, moreover, the screws 116 are tightened or loosened for attaching or detaching the beater 115, which requires a turning key. At the same time, to assure reproducibility, it is necessary to memorize the installation position or orientation of the beater 115 relative to the beater member 110.
But once the drum pedal 90 has been separated into the beater 115 and its other members, it is likely that the beater 115 or the screws 116, which have been loosened and are in a free state, etc. will be lost. If the spring member 150 can be detached from the cam 140, it is convenient for transportation because the drum pedal can be accommodated in a case, provided that the beater 115 is positioned below the operating member 120 or the support. This makes a turning key unnecessary and affords little possibility for the members to be lost.
In FIG. 13, parts which are the same as in FIGS. 9 through 11 have the same reference numbers. The bearing 162 is enclosed in the roller installation hole 161 of the cam member 160. The roller 163 has a hanging part 164 that is freely rotatable on the cam member 160 through the bearing 162. The ring shaped spring member 165 is hung at the hanging part 164 of the roller 163 to provide a spring through the spring member 165.
A washer 166 is held by a tightening nut 167 for the roller 163. The bearing 162 is held in a bearing holder 168. A tightening screw 169 holds the bearing holder 168.
In the structure of FIG. 13, the tension of the spring 107 is added to the hanging part 164 of the roller 163 by the bearing 162, which prevents rotation of the roller 163 with respect to the cam member 160. As the spring member 165 can be detached from the roller 163, moreover, the beater can be located below the support or the operating member, making it easier to transport the drum pedal.
The above described structure, however, applies an excessive load to the bearing 162. This produces inconvenience in the rotation of the roller 163 with respect to the cam member 160 and induces trouble in the bearing 162 or the roller 163, in some cases because the bearing 162 and the spring member 165 are arranged in parallel.